Vortex
Click this link to download Vortex, the program that was used to generate graphics for this site.

John Baker's Excel Spreadsheet
Click this link to download a wonderful Excel spreadsheet that draws variants of the number spiral. It allows you to see versions of the spiral in which the angles of numbers can be any arbitrary power, not merely the square root as is the case with the number spirals shown on this website. This spreadsheet was sent to me by John Baker, publisher of the website Natural Maths.